Numerical investigation of energy performance and cost analysis of Moroccan's building smart walls integrating vanadium dioxide

Thermochromic materials such as vanadium dioxide (VO2) have the capability to regulate their infrared reflectivity depending on ambient temperature. Such smart materials are attractive for applications like smart windows and smart roofs. In this paper, we investigate numerically the impact of tungsten (W) doped VO2 application as a smart outdoor wall layer on the building energy consumption in the Mediterranean climate. Temperature distributions through wall configurations with and without W doped VO2 were calculated using finite differences method implemented in Matlab environment. Calculations take into consideration dynamic variations of W doped VO2 absorptivity depending on outdoor temperature variations. Decrement factor, time lag, transmission and peak loads of cooling and heating were calculated. Results have shown that the indoor surface temperature is attenuated during summer by 2-3 degrees C depending on orientation. Cooling energy saving due to the use of W doped VO2 in summer is around 70% monthly which is equivalent to save $21.6/month of electricity invoiced amount. During winter, W doped VO2 maintains the same value of absorptivity as the un-insulated wall. Thus, results show small differences for indoor surface temperature and heating energy consumption. The application of W doped VO2 in intelligent thermal wall insulation offers a real-time dynamic variation of building's envelope solar absorptivity and makes smart walls concept more feasible.